Hydrodesulfurization of dibenzothiophene and 4,6-dimethyl-dibenzothiophene : Gallium effect over NiMo/Al2O3 sulfided catalysts

Abstract The influence of gallium on alumina-supported NiMo catalysts was investigated by correlating their physicochemical properties with the hydrodesulfurization (HDS) activity of model molecules. The Ga– γ -Al 2 O 3 supports were prepared by impregnation of Ga (0.6–5.9 wt%) on γ -Al 2 O 3 . The NiMo catalysts were prepared following the same method on calcined Ga–Al 2 O 3 . The N 2 -physisorption results showed that Ga did not affect the textural properties of both γ -Al 2 O 3 and NiMo/ γ -Al 2 O 3 . When the Ga–Al 2 O 3 supports were calcined at 723 K all Ga ions presented a high dispersion, forming a different structure than that observed in bulk Ga 2 O 3 . The XPS and the TPR-S showed that the Ga addition modified the structural properties of NiMo depending on the amount of Ga. In the HDS of DBT and 4,6-DMDBT, the Ga–Al 2 O 3 supported NiMo catalysts at loadings of Ga below to 1.2 wt% showed higher activity than that of a NiMo/Al 2 O 3 sample.